U.S. patent number 3,941,632 [Application Number 05/558,722] was granted by the patent office on 1976-03-02 for method and composition for applying a covering to a wall or like substrate.
Invention is credited to Charles C. Fain, William W. Rutledge, Clyde J. Swedenberg.
United States Patent |
3,941,632 |
Swedenberg , et al. |
March 2, 1976 |
Method and composition for applying a covering to a wall or like
substrate
Abstract
Method and composition for applying a surface covering to a wall
or like substrate. The surface covering comprises a flexible strip
or sheet of substantially dry, semi-hydrated gypsum, bonded to a
re-enforcing mesh or lath. The method includes the steps of coating
the rear face of the surface covering sheet with aqueous latex
adhesive in an amount which will transfer sufficient water from the
adhesive to the gypsum to hydrate and set the gypsum, and, at the
same time, invert the latex to a tacky, adherent state; and
applying the adhesive-coated surface covering to the substrate.
Inventors: |
Swedenberg; Clyde J.
(Greenville, SC), Fain; Charles C. (Clemson, SC),
Rutledge; William W. (Greenville, SC) |
Family
ID: |
26871160 |
Appl.
No.: |
05/558,722 |
Filed: |
March 17, 1975 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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175388 |
Aug 26, 1971 |
3887748 |
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Current U.S.
Class: |
156/71; 156/44;
156/333; 427/333; 427/403; 428/140; 428/703; 524/5; 156/327;
156/338; 427/336; 427/407.1; 428/522; 428/906; 428/907 |
Current CPC
Class: |
E04F
13/002 (20130101); Y10S 428/907 (20130101); Y10S
428/906 (20130101); Y10T 428/31935 (20150401); Y10T
428/24347 (20150115) |
Current International
Class: |
E04F
13/00 (20060101); E04F 013/02 () |
Field of
Search: |
;427/333,336,207,403,407
;156/71,333,327,338,39,44 ;106/111 ;428/140,522,538,906,907 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Whitby; Edward G.
Attorney, Agent or Firm: Bailey & Dority
Parent Case Text
This is a division of application Ser. No. 175,388, filed Aug. 26,
1971, now U.S. Pat. No. 3,887,748.
Claims
We claim:
1. A method of applying to a substrate, a surface covering,
comprising a substantially dry, semi-hydrated gypsum, said method
comprising the steps of: coating the gypsum with an aqueous latex
adhesive in an amount which will transfer sufficient water from the
adhesive to the gypsum to hydrate and set the gypsum and invert the
latex, and applying the adhesive-coated surface covering to the
substrate.
2. The method of claim 1, in which the surface covering further
comprises a roll of flexible lath to which the semi-hydrated gypsum
is bonded, said roll of surface covering being unrolled into sheet
form prior to coating it with the latex adhesive.
3. The method of claim 1, in which said aqueous latex adhesive
comprises a polyvinyl acetate water emulsion.
4. The method of claim 1, in which the step of coating the gypsum
includes a plasticizer for the latex adhesive.
5. The method of claim 1, in which the step of coating the gypsum
includes a solvent for the latex adhesive.
Description
BACKGROUND OF THE INVENTION
U.S. Pat. No. 3,185,297 shows a surface covering or building wall
material which includes a semi-hydrated gypsum. A strip of such
material is typically applied to a wall or other substrate by
spraying or coating sufficient water to a sheet of the material to
hydrate the gypsum and cause it to set and harden. While this
material can be adequately applied by a skilled worker, the novice
or amateur worker frequently has difficulty in gauging the
appropriate quantity of water which should be added. Typically, the
novice adds a large excess of water which will run into the floor
and otherwise create a mess. The extra water causes the gypsum to
sag and displace.
SUMMARY OF THE INVENTION
In accordance with the present invention, the amount of water added
to the gypsum can be closely controlled and, at the same time,
additional adhesive is supplied in a tacky form which will greatly
facilitate handling the sheet material and applying it to the
substrate. Sagging of the gypsum and dripping of water is
eliminated. The surface covering will quickly bond to the substrate
without requiring any substantial bonding time.
The surface covering is typically intended for covering an
unfinished wall, such as is formed by concrete blocks. The gypsum
will desirably be provided on its front face with a re-enforcing
mesh or lath which can be given a wallpaper treatment for
decorative purposes.
In its semi-hydrated form, the mixture of gypsum and binder is soft
and flexible, as is the lath. Accordingly, the surface covering can
be furnished in roll form, taking up little space and facilitating
handling.
At the site of application, the surface covering is unrolled and a
coating of latex adhesive is brushed or rolled onto the rear
surface thereof in an amount sufficient to hydrate and set the
gypsum and invert the latex. The adhesive coated gypsum sheet is
then applied to the substrate.
Other objects, features and advantages of the invention will appear
from the following disclosure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Although the disclosure hereof is detailed and exact to enable
those skilled in the art to practice the invention, the physical
embodiments herein disclosed merely exemplify the invention, which
may be embodied in other specific structure. The scope of the
invention is defined in the claims appended hereto.
The disclosure of U.S. Pat. No. 3,185,297 is incorporated herein by
reference. Said patent discloses a building wall material or
surface covering suitable for use in accordance with the present
invention. Commercial embodiments of said patent frequently omit
the fiber batt 5 of said patent and the lath will typically
comprise a fabric mesh on the front face of the gypsum layer, which
re-enforces the gypsum and may also constitute an external surface
therefor which faces the room to give decorative and wallpaper
effects. The covering masks and finishes any rough and unfinished
substrate over which the covering is applied, such as concrete
block, concrete walls, etc.
As aforestated, the surface covering is typically furnished in roll
form inasmuch as the semi-hydrated gypsum-binder is flexible. A
sheet or strip of surface covering is unrolled to a desired size
and the rear surface thereof is coated with an aqueous latex
adhesive in an amount which will transfer sufficient water from the
adhesive to the gypsum to hydrate and set the gypsum and, at the
same time, remove sufficient water from the adhesive to invert the
latex and convert it to a viscous, tacky state, ideally suited to
adhere the wall covering firmly to the substrate.
Inasmuch as the entire hydration requirements of the gypsum are
supplied by the aqueous latex adhesive, it is unnecessary to supply
or otherwise add water to the gypsum. The addition of water is thus
closely controlled and all mess and over-hydration is avoided.
There is a wide variety of various latex adhesives that are
suitable for use in the present invention. However, a polyvinyl
acetate water emulsion has performed admirably because of its ease
of formulation, price and ultimate physical properties. Other latex
adhesives which are also suitable include: vinyl-acetate-ethylene
copolymers, polyvinyl chloride, polymers or copolymers of acrylic
acid, acrylonitrile-butadiene copolymers, chlorinated rubber,
neoprene, polyisobutylene, SB-R rubber, Butyl rubber.
The polyvinyl acetate in the preferred formulation typically
consists of from 45-60% solids, the balance being water.
It is also desirable, but not essential, that a latex plasticizer
be included in the adhesive. Suitable plasticizers include: Abalyn,
acetyl tributyl citrate, butyl benzyl phthalate, butyl phthalyl
butyl glycolate, dibutyl phthalate, dibutyl sebacate, diethyl
phthalate, diethylene glycol dibenzoate, diphenyl phthalate,
dipropylene gylcol, dipropylene glycol dibenzoate, ethyl phthalyl
ethyl glycolate, hexylene glycol, cresyl diphenyl phosphate.
In addition or in lieu of the plasticizer, a latex solvent may be
included. Typical suitable solvents include: ethanol, isopropanol,
methanol, carbon tetrachloride, chloro-benzene, ethylene
dichloride, methylene chloride, perchloro-ethylene,
trichloroethylene, ethyl acetate, dioxane, benzene, toluene,
xylene, acetone, methyl ethyl ketone, nitrobezene,
tetrahydrofuran.
To increase the adhesive characteristic of the coating, a
tackifying resin may be included in the formulation. Suitable
tackifying resins include: Abalyn, belro, dresinol emulsions,
Poly-pale esters, vinsol, Nevillac.
If desired, a thickener can also be added to the formulation.
Suitable thickeners include: casein, guargum, gumarabic,
hydroxyethylcellulose, methylcellulose, polyvinyl alcohol,
starches. Additionally, a fire retardant additive can be included
in the formulation. Additives suitable for this purpose include:
cresyl diphenyl phosphate, cresyl phenyl phosphate and tricresyl
phosphate. A biocide can also be included in the formulation, if
desired. Suitable biocides include: phenol, formaldehyde, and
santobrite.
Typical general formulations of latex adhesive, by weight, are
given in the following examples:
Example I Polyvinyl acetate water emulsion 30 - 95 parts (45% - 60%
solids) Plasticizer 5 - 15 parts Water 0 - 20 parts Example II
Polyvinyl acetate water emulsion 30 - 95 parts (45% - 60% solids)
Solvent 5 - 35 parts Water 0 - 25 parts Example III Polyvinyl
acetate water emulsion 30 - 95 parts (45% - 60% solids) Plasticizer
5 - 15 parts Solvent 0 - 35 parts Water 0 - 25 parts Example IV
Polyvinyl acetate water emulsion 30 - 95 parts (45% - 60% solids)
Tackifying resin 1 - 20 parts Water 0 - 30 parts Example V
Polyvinyl acetate water emulsion 30 - 95 parts (45% - 60% solids)
Thickener 1 - 20 parts Water 0 - 30 parts Example VI Ethylene-vinyl
acetate copolymer water emulsion (45% - 60% solids) 30 - 95 parts
Plasticizer 5 - 15 parts Water 0 - 20 parts Example VII
Ethylene-vinyl acetate copolymer water emulsion (45% - 60% solids)
30 - 95 parts Tackifying resin 1 - 20 parts Water 0 - 50 parts
For optimum results, substantially all of the requirements of the
gypsum for water should be satisfied by the water present in the
adhesive and enough of the water should be removed from the
adhesive to invert the latex.
Three parts of water are usually required to set 10 parts of gypsum
plaster by weight. Accordingly, if, for example, the gypsum layer
of the surface covering has 14 ounces of plaster per square yard
4.2 ounces of water should be supplied in the adhesive per square
yard when the adhesive coating is applied. Assuming an adhesive
with a real viscosity of 40 poise, 15 square yards of surface
covering material is coated with 1 gallon of adhesive. This means
that 8.5 ounces of adhesive is applied per square yard of the
gypsum. Assuming the adhesive contains 49% water, this will result
in a sufficient quantity of water in the adhesive to hydrate and
set the plaster. By the same token, an adhesive of 100 poise, which
covers 10 square yards per gallon, must have a water content of 34%
to completely hydrate and set the gypsum.
Ideally there should be an excess of about 10% water in the
adhesive to allow for loss due to evaporation, handling and
shipping.
In for foregoing examples, water is present both in the water
emulsion and in the additional water component of the
formulation.
In the foregoing examples, a sufficient quantity of water has been
transferred from the latex emulsion to the gypsum to cause
inversion of the latex. Typically, removal of 65 - 75% of the water
from a polyvinyl acetate water emulsion adhesive will cause
inversion. In the case of polyvinyl acetate, the adhesive will
typically change from a white, milky-appearing liquid (5 - 100
poise viscosity) to a clear, semi-solid cabout 100,000 poise
viscosity) within a few seconds of application to the gypsum and
transfer of water thereto. The effect is the production on the
rearface of the wall covering of a continuous film of tacky
adhesive somewhat in the nature of a pressure-sensitive film. Prior
to coating the gypsum, the adhesive has low viscosity and low tack,
thus making it easily-handled and applied. However, within a few
seconds after application to the gypsum, the adhesive has the
characteristics of a high-viscolsity and highly tacky adhesive. The
covering is thus adhered to the substrate substantially
instantaneously and with ease and facility by the worker.
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